Ending of Vera Menchik vs Albert Becker? [beginner question]

Hi, I am a chess noob looking at the end of this famous game: https://www.chessgames.com/perl/chessgame?gid=1066877&comp=1, but I do not understand how white has won. To me it seems there are quite a few places black's king could go?

Could someone explain?

The king and rook are forked by the pawn. Black is going to be down a full rook. 

I can see that the king and rook are forked by the pawn, but it's not clear to me that here is where the game ends? Is it more like "to advanced chess players it's clear there is no series of moves that would not end in a checkmate of black's king"?

Well it may still be many moves until checkmate, but when strong players are down by a full piece and have no chance to attack themselves then they resign. To play on would be insulting to the player who is winning. If you are a beginner though I suggest you play all your games right to the end - your opponents (other beginners) may blunder and you can learn checkmating patterns etc even in defeat. 

I had no idea players in higher level matched in such a position would resign. Good to know, I am significantly less confused now.